The process of manufacturing semiconductor substrates (hereinafter, simply referred to as “substrates”) conventionally involves various types of processing performed on substrates having insulation films such as an oxide film by a substrate processing apparatus. One example is cleaning processing for removing particles or the like adhering to the surface of a substrate by supplying a cleaning liquid to the substrate surface.
Japanese Patent Application Laid-Open No. 11-329936 (Document 1) discloses a substrate processing apparatus for ejecting a photoresist liquid toward a substrate from a single processing liquid supply nozzle disposed above the substrate. The substrate processing apparatus includes a CCD camera directed between the processing liquid supply nozzle and the substrate in order to capture an image of a liquid column of the processing liquid ejected from the processing liquid supply nozzle. The width of the captured liquid column of the processing liquid (i.e., the width of ejection of the processing liquid from the processing liquid supply nozzle) is compared with a predetermined reference width, and a captured liquid column smaller in width than the reference width is detected as an ejection abnormality.
Japanese Patent Application Laid-Open No. 2003-272986 (Document 2) discloses a substrate processing apparatus for applying a developer onto a stationary held substrate from slit outlets of a developer-discharge nozzle. The substrate processing apparatus includes an illuminator for irradiating a substrate with light and a light detection part for detecting light reflected off a processing liquid on a substrate. The light detection part captures an image of the entire surface of a substrate with a CCD camera and detects a developer supply defective area where the developer has not collected on the substrate on the basis of a difference in lightness between the developer supply defective area and the other areas.
Japanese Patent Application Laid-Open No. 2008-135679 (Document 3) discloses a liquid treatment apparatus for supplying a coating liquid onto a substrate from a coating liquid nozzle. The liquid treatment apparatus is configured such that the coating liquid nozzle is transported between a position above the substrate and a nozzle bus serving as a standby position, and an image of the tip portion of the coating liquid nozzle is captured during transport. On the basis of the result of the image capture, the liquid treatment apparatus detects occurrence of trickling or dripping of liquid from the tip portion of the coating liquid nozzle.
Japanese Patent Application Laid-Open No. 2012-9812 (Document 4) discloses a liquid processing device for supplying a treatment liquid onto a substrate from a treatment liquid nozzle. The liquid processing device includes 11 nozzles that are arranged in a straight line and held by a nozzle head part. Areas from the tip portions of these nozzles to the surface of a substrate is irradiated with a line of laser light, and images of liquid columns of a resist liquid ejected from the respective nozzles are captured with a camera directed to the areas. Then, the result of the image capture is compared with reference information, which is obtained in advance by capturing images of the resist liquid ejected normally from the nozzles, so as to determine whether or not the resist liquid is ejected from the nozzles and whether or not the ejection state has changed.
Japanese Patent Application Laid-Open No. 2012-209513 (Document 5) discloses a substrate processing apparatus for ejecting fine droplets of a processing liquid toward a substrate from a plurality of outlets. The substrate processing apparatus includes a plurality of outlet rows, each having a plurality of outlets arranged in a line.
With the apparatus as disclosed in Document 5, a plurality of outlet rows each having a large number of outlets are arranged in a direction that intersects with the direction of arrangement of the outlets, and accordingly fine droplets ejected from the respective outlets overlap one another. Thus, even if the user attempts to determine whether or not the processing liquid is ejected from each of the outlets, it is not easy to identify which droplet correspond to which outlet.
One example of ejection abnormalities of fine droplets is oblique ejection that refers to ejection in a direction deviating from a predetermined ejection direction. As a method of detecting such oblique ejection, it is conceivable to compare the intervals between fine droplets with a normal value. It is, however, not easy to judge either normal ejection or oblique ejection because the intervals between fine droplets ejected from outlets located close to an observation point looks large while the intervals between fine droplets ejected from outlets located furthest from the observation point looks small. The size of each fine droplet also varies depending on the distance from the observation point.